Diaper with elastic margins

Abstract

The present invention is an elastic leg diaper and a method and equipment for its manufacture. A preferred form of the diaper uses for the entire moisture impermeable backing sheet an elastomeric material of the type that is heat unstable and relatively inelastic in its unshrunk form and stable and relatively elastic in its heat shrunk form. Numerous materials of this type are available. Included among them are block copolymers which include a rubbery material as one component, polyurethanes, and irradiated polyethylene. Diapers made using one of these materials as a backing sheet can be conventionally assembled. After assembly, the marginal areas, which may be either or both of the transverse and longitudinal margins, may be heated to a sufficient temperature for shrinkage to occur in the backing sheet. This shrinkage will only occur when the backing sheet is unrestrained. The method provides for the maintenance of longitudinal tension in the central portion of an end-to-end assembly of diaper units while relaxing the edge tension on the units. This is accomplished in the present diaper making machine by passing the assembly over a series of rollers which are of cylindrical form in the central portion and are tapered at each end. The marginal portions overhang the tapered portion where they are free to shrink after heating. If an elastic waist construction is desired, the diapers are similarly heated in an transverse direction whereupon any transverse tension is relaxed to enable transverse shrinkage to occur. While the preferred diaper uses the heat shrinkable material as the entire backing film, it is within the scope of the invention to insert ribbons of this material along the appropriate marginal edges of the diapers and use conventional backing film materials.

Dependencies are inferred from the claim text.